Gravel Tyre Clearance (and the lack of)

They fit obviously as the wheels turn. However if the wheels go a fraction out of true or you get any sort of mud on the tyres and grit(gravel?) then at the very least you're taking paint off the frame and at worst eroding the aluminium.

I guess out of the saddle riding will enduce flex from the wheel and start the above process anyway

Hmm I guess I can only give them a try and see what happens. I've never had a wheel go out of true in all the years on bikes luckily though!

I'm struggling to think what other frames have similar traits to this, but with a little more clearance. A quick late night search I discovered a Giant Revolt X (2023) has clearance for 53c but might be difficult to get a frame only.

Off the top of my head Brother Cycles Mehteh is 56mm clearance and the Fairlight Secan is over 60mm 

I think those were on my original list before I got the Fustle. I've been riding it a lot and it's a great bike! I'd just like a little more clearance on this wheel/tyre set up 🙂

I'll compare the geometry and see what they look like.

This is interesting as Fustle have been popping up on my feed the last couple of weeks so I'd been eyeing them up. 

Then I got distracted by the Secan thread....

I thought 4mm (per side, not total) was the 'international standard' for tyre clearance, am sure I read an article on the Cervelo site to that effect.

My CX bike/winter gravel bike has less than that. I've definitely worn right through the paint through flex or abrasive grit, but I heli-taped over it and the tape is still intact, so presumably the same effect that wore through paint can't wear through heli-tape!

Gives me faith that you'll not wear through the frame anyway, at worst paintwork 👍

Secan is lovely, but then I saw the price of a frame with headset etc!

Brother Meteh looks like similar clearance to what I've already got.  I might end up having to ditch the 2.0 Racekings if they are too big.

The other question would be what 50c gravel tyres could I try and would they size up smaller than a 2.0 mtb tyre?

I’d not worry about the wheel going out of shape, but I would flex under pedalling. And general mud, that’s going to eat into the frame either way I’d say

When I got mine my requirements were 700x50c quoted with the intention to run max 700x45c.  If I want/need anything wider/nobblier then I have a hardtail for that duty, with 2.1" Crosskings.

Had issues with my (ancient) Cotic Soul running a tyre too close to the limit, not due to wheel going out of true or flexing under my immense power 😉 but due to stones getting stuck in the side nobbles of the tyre, and scraping away the paint on the inside of the chain stays. Maxxis were the worst for that.  I didn't want a repeat on whichever gravel bike I got (also had Secan and Cascade on my shortlist as well as the Causeway)

I have Schwalbe G-One allround 45c on DT Swiss GR1600's (25mm internal width?) and can squeeze a small finger in between the tyre and the stays and that bolt.  I reckon a 50c version of that would fit, but I wouldn't be wanting anything more chunky in there. I imagine that a 50c gravel tyre would be fine, but a 50c MTB tyre is at your own risk (hence a * on the website for the specs)

I guess the cost free option at this point would be to try the 45c Pirelli Cinturato that are currently on my cheap spare wheels if the current tyres start to cause issues.

Will be interesting to see how they size up on a 27mm rim anyway. I'm keen on keeping the frame and wheels, so it'll be the tyres that I will have to compromise on for the time being 🙁

FYi I have a Causeway and am running 50mm WTB resolutes on 25mm rims and there's ample clearance for tyres. Been running them through winter too

Yeah, you're the reason I ended up going for the Causeway 🙂

27mm rim shouldn't really make a massive difference then, so I bet 50c gravel tyres would leave me with decent clearance. It's more the height of the tyre that I'm struggling with on the Racekings.

I wouldn't want to ride that. Mud and gravel will eat the chainstays, especially with any flex at all. In my experience, some tyres also stretch a little bit as they age, so any clearance you currently have could reduce further.

I don’t think those tyres fit in that frame.

https://www.bicyclerollingresistance.com/ might give you some real world tyre measurements that help.

Rim width more or less adds to the circumference rather than the diameter- not <quite>, but a good overall rule is that each 3mm of extra rim adds roughly 1mm to diamater. Tread shape complicates that but not so much with gravel tyres.

To me, that tyre probably doesn't fit but it'd depend loads on your riding and conditions and also on how cloggy the specific tyre is, I'm pretty certain that some people would be absolutely fine and some people would declare it obviously unworkable and terrible.

The sooner gravel bikes morph into early 29er geometry and clearances, the sooner we'll have proper bikes for UK trails which generally aren't nicely graded gravel.
We used to call dropbar 29ers monstercrossers and they were ideal for our trails. With the improvements in brakes and gearing a modern version would make the perfect gravel bike with a supple 2.35" tyre with small knobs IMO. (The small knobs on the tyre, not the bike 🙂 ) 

What actual width are those tyres, not stated, but measured?

FWIW I've just fitted Schwalbe Thunder Burt 29x2.1's to my Free Ranger, on 25mm internal rims.  They measure up at 51mm.

I thought 4mm (per side, not total) was the 'international standard' for tyre clearance, am sure I read an article on the Cervelo site to that effect.

ISO spec for a road bike is 4mm matched to tighter wheel accuracy specs, for everything else it's 6mm with a bit more wheel wobble tolerated. For a gravel bike 6mm would be more practical but since a gravel bike is closer to the scope of a road bike in most areas 4mm may be ok. 

I guess the cost free option at this point would be to try the 45c Pirelli Cinturato

I was gonna say a 45mm rear tyre might be the most cost-effective option, as others have said - dirt and wheel flex would see those seat stays getting mullered, if it's as tight as it looks.

I have 45mm tyres on 25mm internal rims and they are lovely, I don't think an extra 2mm internal width would render the rear unrideable.

I'd ride that. 

But i have been know to take files and clamps to frames to make tyres fit. You can't trash a frame more than taking a bastard to it 🤣. Well you can... I have just cut out bridges completely.

Just file the boss rim off and see what happens. 

I wouldn't be worried about having only 4mm of clearance vertically, as I tend to knock my wheels out of true only laterally. And you would only wear at the boss of the mudguard bolt anyway.

Do you only have 4mm clearance at the sides as well? That would worry me, but I have run 5-6mm before without issues (I don't ride in really muddy conditions though).

The best thing would prob be to get a 45mm in there and leave the 50mm up front. You could get one of the new conti things to match:

https://r2-bike.com/CONTINENTAL-Tire-Terra-Adventure-28-x-175-45-622-E-25-Trail-Grip-black  

Which version of the Raceking is it?

Just stick on some stainless steel strips on the chain stays, it'll be reet 😉 

Haha a proper mixed bag of unrideable death trap to plenty of room to spare!

I think I'm leaning towards removing and putting the 45c tyres on there.  I was going to have a little test ride locally tomorrow to see what happens, but at the same time I don't want to cause any damage.

They are Raceking 2.0 pure grip/shield wall ones. I can't find my caliper to measure the true width at the moment, but it's more the height of the tyre that's concerning.

The pic at the start is the chainstay brace near the seat tube at the bottom, that's where it's cutting it fine.

** After having a second look the sides actually look a little too close for comfort too at the back of the stays. I'd been so concerned with the middle, I've not even noticed how close they are at the sides 🙁

Is clearance at the front OK? I don't see any reason to go down to 45mm up front if so

Yeah, looks like plenty of clearance up front tbh. Thing is, I'm a bit of a tart and the mixed size/style of tyre would wind me up 🙂

I've taken a dremel sandpaper disk to the side knobs in a similar situation (MTB where lots of mud is a given). Hold it in the right place with the wheel off the ground and it spins round and does the job quickly and neatly. But I can't see clearly from the photos if just taking the corner off is ok.

Posted by: johnw1984

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Yeah, looks like plenty of clearance up front tbh. Thing is, I'm a bit of a tart and the mixed size/style of tyre would wind me up 🙂

I empathise with that. For me though, I can handle mix sizes no problem (I used to have a Stooge with 29 x 2.4" rear! and 29 x 3.0" front), but I can't handle mixing brands with different sidewall patterns.

And those lunatics that run a black tyre one end and a tanwall the other keep me up at night.

Hmm, the other tyres are tanwalls haha.

Against my better judgement and the more cautious advice on here, I went for a decent test ride around Rivi today with the big tyres.

I'm pleased to report that there isn't a mark on the inside of the chainstays, so that's good. The not-so-good is that the front tyre has a small warp! I don't notice it though unless I happen to look down at it 🙁

I'll continue to test and keep a close eye on the rear I think now. They honestly felt fantastic on the rougher stuff and much faster rolling offroad!